The New Zealand CT-4A Airtrainer can trace its ancestry from the Australian Victa Airtourer, designed by Henry Millicer in the 1950s. The Millicer Airtourer, powered by a 65 hp Continental engine, first flew on 31 March 1959, and the production rights were then purchased by Victa Consolidated Industries.

The Victa Airtourer VH-MVA, powered by a 100 hp Continental, flew on 12 December 1961, and this was developed into the 115 hp Lycoming version which flew in September 1962. Victa produced 172 Airtourers up to the end of 1966. When the company was unable to obtain either a government subsidy or tariff protection against foreign competition, the complete project was sold to Aero Engine Services Ltd (AESL) of Hamilton, New Zealand. The four-seat Victa Aircruiser project was similarly sold to AESL in 1970.

The first AESL Airtourer, registered ZK-COW, flew in mid-1967 and was a 115 hp Airtourer designated model T2. The T3 had a 130 hp Continental, the T4 a 150 hp Lycoming with a fixed-pitch propeller, and the T5 had a constant-speed propeller. The T6 model, with an increase in weight over the T5, finished the Airtourer production at 80 aircraft, including four for the Royal New Zealand Air Force and six for the Singapore Air Force. These six T6 aircraft were later sold by Singapore and came to Australia on the civil register.

In 1969 an AESL T4, ZK-CJN, flew to Australia for RAAF evaluation. RAAF Air Staff Requirement 67, issued in May 1971, laid down the requirements for a basic trainer to replace the Winjeel, and AESL responded with a development of the Aircruiser powered by a 210 hp Continental. Known as the CT-4, the prototype, ZK-DGY, flew on 23 February 1972. The CT-4 was selected by the RAAF over the Scottish Aviation Bulldog, and the order for 37 aircraft at a cost of $3.2 million was announced on 24 July 1972. The Royal Thai Air Force, which had been awaiting the Australian choice, then ordered 24 CT-4s, and these were delivered before the RAAF batch.

The first production CT-4 was delivered to the Thai Government in December 1972, followed by the Royal Thai Air Force order which increased to 25 aircraft (AESL numbers 2 to 26). In 1973 NZ Aerospace Industries (NZAI) was formed by the merger of AESL and Air Parts (NZ) Ltd, manufacturer of the Fletcher agricultural aircraft. Production then commenced in 1974 of the 37 NZAI CT-4As of the RAAF (A19-027 to A19-063).

The first aircraft, A19-027, with NZ ferry registration ZK-DZP, was ferried from Hamilton to RAAF Williamtown on 8 February 1975. This aircraft was officially accepted by the RAAF at Bankstown on 15 January. Each RAAF CT-4 was ferried across the Tasman with long-range tanks, staging through Norfolk or Lord Howe Islands. Most of the ferries were flown by the NZAI Chief Pilot, Cliff Tait, who describes the hazards and loneliness of long over-water single-engined crossings in his book, "Water Under My Wings". Initial deliveries were to the Central Flying School at RAAF East Sale for instructor conversion, followed in late 1975 by the first basic course at No 1 Flying Training School at RAAF Point Cook. Also during 1975, an Aircraft Research and Development Unit CT-4 completed hot weather trials at Tindal, near Katherine in the Northern Territory.

The next production batch of 14 had been ordered for a Swiss flying club, but it was discovered in early 1976 that the ultimate customer was the Rhodesian Air Force, then under a United Nations embargo. The New Zealand Government halted export of these aircraft, and they were stored by NZAI. In late 1980 the RAAF arranged to buy this batch to supplement the surviving 35 CT-4s, and, serialled A19-064 to A19-077, these were delivered from July 1981 to late 1982. In April 1982, the seventh of this order, ZK-EUS (A19-070), was ferried by Cliff Tait to complete his 100th single-engined Tasman Sea crossing.

In 1982 Pacific Aerospace Corporation (PAC) was formed when NZAI went into receivership. The final production run of the CT-4A was for the RNZAF, and with the last of this batch, serialled NZ1948, deliveries stood at 96 aircraft.

Possibly the greatest CT-4 fly-past in the RAAF was at Point Cook on 1 May 1988 for the RAAF Anniversary Air Show, when 24 No 1 Flying Training School aircraft flew over in an "88" formation. In November 1989, a No 1 Flying Training School CT-4, A19-040, re-enacted the first cross-continental flight by Captain H.N. Wrigley, who flew a BE-2e biplane from Point Cook to Darwin in 1919.

The CT-4 was phased out of service at No 1 Flying Training School in December 1992, and this marked a change in policy for RAAF basic pilot training. Civil contractors now conduct RAAF and Royal Australian Navy flight grading, in addition to tri-Service basic training at the Australian Defence Force Basic Flying Training School, located at the BAE Systems Flight Training College at Tamworth, New South Wales.